PHILADELPHIA -- The Phillies hope the eighth inning is routine and ordinary in 2013.

It had become a minefield in 2012. They blew a big league-leading 13 leads in the eighth last season, a truly eye-popping figure considering they finished seven games behind the St. Louis Cardinals for the second National League Wild Card. The Phils knew they could not afford to enter next season with mostly unproven relievers in that role. They also knew they could not take a chance on another low-risk, high-reward reliever like Chad Qualls.

They needed somebody with a recent track record of success.

So Thursday they announced they had signed right-hander Mike Adams to a two-year, $12 million contract, which includes a vesting option for 2015. If Adams makes 120 appearances in 2013-14 -- with 60 appearances in 2014 -- the contract vests for $6.5 million. If he makes 65 appearances in '14, it vests for $6 million. The Phillies also have a club option for $6 million, if Adams doesn't hit those marks.

"If all goes the way I see it, by the end of my contract it's going to be a bargain," Adams said.

The Phils would welcome that. Adams, 34, went 5-3 with a 3.27 ERA and one save in 61 appearances last season with the Rangers. He has a 1.84 ERA and 112 holds since the beginning of the 2009 season, which are the best marks in baseball in those categories among relievers with 200 or more innings pitched.

But unlike the low-risk Qualls, this signing carries some risk.

Adams had thoracic outlet syndrome surgery in October, which involved the first rib below his right clavicle being removed, although he said he should be ready by Opening Day.

"That first rib starts squeezing the clavicle," Adams explained. "You have a main artery and a nerve that runs through there, so when you start squeezing those, that nerve starts shooting pain through your body. I was having headaches constantly for three weeks. My trap was hurting, my pec, the middle of my back was hurt. I was having some numbness and tingling in my biceps and forearm, and it was something that was pretty bad. The symptoms were pretty bad.

"Once I had the surgery to take care of it, some of the shoulder pain was gone within two days. It took a little while longer for a lot of the other symptoms to go away, but they said in time it will. They say the nerves have been so freaked out they needed time to recover. It wasn't until about three or four weeks ago that I really started to feel the symptoms go away."

Adams started throwing a baseball a few weeks ago. He told his agent, Josh Yates, he felt great, and he would be comfortable signing a two-year deal with a vesting option because he did not consider it a risk.

But Phillies special assistant to the general manager Charley Kerfeld watched Adams throw recently to be certain. Adams wasn't throwing off the mound, but Kerfeld at least could see how loose his arm looked.

It looked good.

"Last year was a struggle for me," Adams said. "I didn't know what was happening. I just thought I was having some shoulder discomfort issues. The majority of the season, I battled and I battled not having the same stuff I had previously. I didn't have a good feel for the ball. There were times where I didn't know how to grip a fastball because I didn't have the feel. That's the symptoms of TOS. By the end of the year, it really caught up to me. My arm felt like it weighed five or six pounds more than it normally did. The ball felt like it weighed three pounds. My last outing, I felt like I was pitching a shot put.

"The trainer for Texas told me that once I get a few weeks into the rehab process, I'm going to feel like I have a new arm. That's really how it feels right now. I'm three weeks into my throwing program. Throwing now feels so much better than it did last year."

If Adams, who said he nearly signed with an NL East rival, bounces back like he believes, the Phils should have a formidable 1-2 punch in the late innings with closer Jonathan Papelbon.

"We've had our eye on Mike for a long time," general manager Ruben Amaro Jr. said. "He's put himself in position to be one of the most consistent back-end guys in the game, and that's why it was an important signing to us. There is no question that there is some risk involved. As a group, we talked to our people about the TOS and how that might affect him short term and long term, but I think ultimately, we feel comfortable enough and felt comfortable with the procedure and the follow-up information that we got. While there is some risk to it, it probably was a good risk. This is a guy who can probably solidify our bullpen."

Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.